Apple cinnamon: Stir in 1 apple, chopped, and 1/2 teaspoon cinnamon with the water.
Pumpkin spice: Stir in 1 cup pumpkin puree, 1/4 cup maple syrup, and 3/4 teaspoon pumpkin pie spice with the water.
Peanut butter–banana: Stir 1/4 cup creamy peanut butter into the finished oatmeal. Top each serving with banana slices.
Blueberry almond/pecan: Top each serving with a handful of fresh blueberries, a scattering of toasted sliced almonds or pecans, and a drizzle of honey.
Savory sesame soy: Omit the salt. Stir in 2 tablespoons soy sauce and add 1/2 teaspoon toasted sesame oil with the water. Serve topped with a fried egg.